Monday, February 21, 2011

It's been several years since EPA issued one of its reports on annual pesticide sales and use. I find these statistics interesting, if for nothing more than quoting in general talks on pesticides or for literature reviews preliminary to asking someone for money. So I am glad to see that budget cutbacks haven't completely eliminated this service, and we have some more recent figures to study (2006-2007).

If you had to guess what pesticide was used more than any other by the Government/Industry/Commercial sector, what would you guess? The answer, according to this report is the herbicide 2,4-D, followed by the popular glyphosate, or Roundup®. Insecticides barely make the top ten list, with malathion and sulfuryl flouride (Vikane®) coming in at positions 9 and 10, respectively.

The report illustrates the dramatic decline in organophosphate use, as well as the overall decline in pounds of insecticide used by the commercial/governmental sector. Interestingly, the overall amount of pesticides used in the home and garden sector has been pretty steady over the past 20 years.

The value of the pesticide market in the U.S. for 2007 was $12.5 billion. Within the commercial/governmental/industry sector (which you belong to) the pesticide market was worth $1.9 billion, and the insecticide market by itself, $709 million.

Tuesday, February 15, 2011

A recent study in the March issue of the journal Pediatrics [vol. 127(3): e693-e700] reports on a correlation between pre-natal exposure to the common synergist piperonyl butoxide (PBO) and delayed mental development among 3 year-old children. In a review of the article, e! Science News reported the author as saying that the drop in IQ points [among children whose mothers had higher PBO exposure] is similar to that observed in response to lead exposure. Megan Horton, of the Mailman School of Public Health and lead researcher, said the drop, while not severe enough to affect a child's overall function "...is educationally meaningful..." Going a little further out on a limb, she added that it "...could shift the distribution of children in the society who would be in need of early intervention services".

The results of this study should be considered preliminary, and certainly indicate the need for more research. Similar to the study on ADHD that I reported on last year, the data shows a correlation, but does not indicate a cause and effect relationship. Further studies may or may not substantiate the correlation. Furthermore, the authors note that this is the first study to ever look at the health effects of PBO on humans (previous studies, presumably having been done only on laboratory animals).

The paper brings up an interesting issue with regard to the pest control industry. What criteria should we use to make decisions about the kinds of pesticides we use in our business? Should a new study impact the way we use chemicals? Or should we always just follow the lead of the EPA when it permits or restricts use of a pesticide?

Ultimately, and from a legal point of view, the EPA is our guide. The EPA has hundreds of toxicologists trained to look at studies such as these and determine whether there is enough data to justify a change in label requirements. However, the process of revoking a use, or a pesticide, can take years.

The biggest question I had about this study concerned the mothers' exposure to PBO. Piperonyl butoxide in itself is not toxic to insects. Rather, it is added to a few insecticides--most notably pyrethrins--to prevent insects from detoxifying the actual insecticide. It turns out that pyrethrins, by themselves, are great at quickly knocking down, but not killing, most insects. Adding PBO to pyrethrins merely keeps insects down for the count.

Most pyrethrins formulations, including a number of over the counter (OTC) consumer products, contain PBO in low concentrations--usually less than 5%. In recent years, however, some professional products have included higher percentages of PBO (e.g., 60%). I've never fully understood the reason for the popularity of this mixture, given that PBO is non-insecticidal and that only small amounts of it are needed to synergize pyrethrins. From what I can gather informally, PBO mixtures are being used increasingly by frustrated PMPs for bed bugs. But I've always been under the impression that only a small percentage of residential pesticide applications by professionals used PBO. It was surprising to me therefore to read that PBO was detected in 75% of personal air samples collected in the study.

The study assumes PBO was used as a synergist with permethrin; however, permethrin is not normally sold with PBO. Unless a lot of New York PMPs are using this combination (perhaps in bed bug applications?) I am skeptical that this use pattern is common throughout the country. It's also possible that the PBO is coming from use of OTC products by the householders themselves. Or there might be some non-pest control source of PBO. In any case, it seems like one of the first regulatory steps would be to find out where PBO exposure is coming from. [Any insights in this regard from readers would be welcome!]

In the meantime, in my opinion it would be prudent to consider limiting use of products with high percentages of PBO in accounts with pregnant women or infants. I'm not convinced yet that PBO is posing a health risk to the unborn or very young; but in most cases there are good alternatives. Our industry should be placing highest value on customer safety, so why don't we take a proactive lead on this one?

While most of us were waking up to snow and ice earlier this month, a number of researchers and government officials trekked to Washington, DC for the second National Bed Bug Summit. Unfortunately, this was a meeting I had to miss; but the good news is that the presentations have been made available through the Entomological Society of America's (ESA's) new urban entomology network site.

The links provided are merely Acrobat (pdf) copies of presentations made at the meeting, but you can get an idea of the flavor of the event by scanning the slides. There is no narration, so you don't get the full content of the presentations, but there is still considerable information in the slides. Also, you might want to contact the speaker directly if you have a specific question about a presentation. This method is sure a lot easier than negotiating long lines at airports during blizzard season.

Friday, February 11, 2011

One of our Texas school districts recently received the following letter:

Dear Superintendent ___:

I am a director with PETA’s Cruelty Investigations Department. I hope this email finds you well. Thank you for speaking with my cruelty caseworker... regarding the use of glue traps by the ___ Independent School District. As he mentioned, the Centers for Disease Control (CDC) warn against glue trap usage due to the disease risks they pose. Glue traps are also exceptionally cruel. If lethal methods are insisted upon, the D-Con Ultra Set Covered Mouse/Rat Traps http://www.d-conproducts.com/traps/ultra-set.html and Victor Electronic traps http://www.victorpest.com/store/rodent-control/electronic-mouse-trap are cost-effective, easily obtained, sanitary, and far less cruel.

May we hear from you that the ___ Independent School District has joined the countless businesses, corporations, and school districts that have sworn off using cruel glue traps?

Now glue boards, by themselves, are not my favorite way to control rodents. As commonly deployed, they do not typically kill the animal quickly, they need checking regularly and they may not leave a good impression on a customer who discovers a captured rodent on a glue board still alive.

I have less sympathy, however, with the argument that killing rats and mice is unethical. When house mice, roof and Norway rats invade a home, school or business, there's no question in my mind who has to go. It is more unethical, in my opinion, to release these pests (that prefer and are drawn to human habitations) back into the environment where they are likely to become another person's problem.

Thank you for your concern about the ethical treatment of animals. Most of the people I know share many of your concerns and have no desire to cause unnecessary pain or suffering of any animal, including those that we consider pests. Nevertheless, we may have a fundamental difference of opinion about the necessity to kill and eliminate rodents from human living environments.

Live rodents have serious aesthetic, economic, and health impacts on schools. Any rodent activity in our facilities is considered highly unacceptable by our staff and our community. Rodents damage school property via their chewing activity--which also puts schools at increased risk of fire (due to shorts caused by damage to electrical wiring). Perhaps most importantly, rodents contaminate classrooms, offices, food and food preparation surfaces with their feces and urine. Rodents are implicated in the transmission of over 55 human disease pathogens. A single house mouse produces 50 to 75 droppings and over 3,000 micro-droplets of urine daily. These potentially bacteria- and virus-contaminated feces and urine droplets are dispersed wherever the mouse travels in a classroom, office or kitchen area.

Regarding tactics, our district's main emphasis in on preventing rodent infestations. The highest priority of our rodent control program consists of sealing potential rodent entry points into buildings, and eliminating conditions that are attractive to rodents (clutter, poor sanitation around dumpsters, food spillage, etc.).

Unfortunately, experience has shown that despite our best efforts, some buildings and grounds will become rodent infested. When this occurs we look for the most effective, economical and humane methods for control. Some of these tactics include snap and multiple catch traps, solid and liquid baits, tracking powders, glue boards and glue trays. It's important to note that none of these tactics by themselves provide complete control of rodents. For this reason we use an integrated approach.

Our district's pest management program is based on a strategy known as integrated pest management (IPM). The IPM concept recognizes the limitations of single tactic approaches to pest control, and tries to make use of simultaneous, multiple control tactics. Glue boards and glue trays are not the principal method used by our district to control rodents. Glue traps tend to be less effective for house mice than snap traps, and rats are more difficult to catch and contain on these devices. Nevertheless, glue traps have useful applications. For example, glue boards may be the most effective choice in tight quarters where snap traps cannot fit. They are also useful in combination with multiple catch traps, where they facilitate cleaning and rodent removal. In addition, glue boards help contain biohazards such as the carcasses themselves, feces and ectoparasites (e.g., fleas and mites) carried by many rodents.

When glue boards are used, our staff makes every effort to check them frequently. Any live animals found trapped in glue are killed quickly and humanely. Glue boards are only deployed and monitored by licensed professionals on our staff or by licensed contractors. We presume that the CDC recommendations you refer to are the ones directed to homeowners who do not have the same level of training and professionalism as our staff. Our staff are trained to place and service traps in a manner that minimizes the risk of disease transmission (use of gloves, putting glue boards inside bait stations and inside multiple-catch traps, etc.).

Thank you for your suggestion concerning electronic traps. These traps have great potential for rodent control programs--especially for mice. They can certainly supplement, but not replace all other lethal methods in an IPM program. It is also important to understand that electrocuting traps do not guarantee immediate kill for rats. In addition such traps are up to 60 times (rats) and 150 times (mice) more expensive than snap or suffocation traps, according to one evaluation. Nevertheless, some of our colleagues find that electrocuting traps with wireless alert capabilities can be worth the higher cost by eliminating the need of labor expenses for repeated visits to check empty traps. We will continue to evaluate the use of these traps, as we do for all control options.

We believe that our efforts in preventing rodent problems first, and correcting infestations quickly, is the most humane approach to rodent control. We will continue to search for and evaluate better methods to do this, and welcome any additional ideas or suggestions you might be able to provide.

If your district or pest control business is not currently using the IPM approach to managing rodent control, if it is not emphasizing prevention, and if it is not checking glue boards and multiple catch traps frequently, perhaps it's time to make some changes. But don't doubt for a moment that when you trap and eliminate rodents you are providing a useful service to your community. To do anything less would be cruel indeed.

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About Me

I have served as entomology specialist for Texas AgriLife Extension since 1989. I get to work with, and for, a bunch of great people including pest management professionals, school facilities managers, extension volunteers, researchers and other extension professionals. My areas of specialty center on research on insects affecting man including spiders, scorpions, fire ants, termites and others. My program also focuses on training school maintenance professionals in principles of integrated pest management (IPM). Our goal is to make schools healthier, cleaner places to study and live.